German Patent Document No. 43 20 780 refers to a semiconductor diode, in which the doping profile at the edges of the diode deviates from the doping profile at the center. This can be used so that in reverse-biased operation the voltage breakdown, which sets in at breakdown voltage UZ, occurs only in the central part of the diode and not at the edge. This results in a high robustness in operation since no avalanche breakdown can occur at the chip edges.
German Patent Document No. 43 20 780 further refers to a semiconductor system having a p-n junction, in particular a diode, which takes the form of a chip having an edge region, which is constructed of a first layer of a first conductivity type and a second layer of the opposite conductivity type, the second layer being made up of at least two sublayers. In this instance, the first sublayer has a first dopant concentration, while the second sublayer has a second dopant concentration which is lower than the first dopant concentration. Together with the first layer, both sublayers form a p-n junction, the p-n junction of the first layer with the first sublayer being formed exclusively in the interior of the chip and the p-n junction between the first layer and the second sublayer being formed in the edge region of the chip.
The available semiconductor system has the distinction of having a high robustness in operation since, due to the special form of the doping profile in the edge region, no voltage breakdown occurs in the edge region in reverse-biased operation of the semiconductor system. It is disadvantageous, however, that this semiconductor system has a relatively high electrical resistance as a result of its lightly doped middle layer. This high electrical resistance causes an undesired voltage drop, which has an adverse effect particularly in breakdown operation. This is all the more pronounced the higher the breakdown voltage UZ of the semiconductor system. For this reason, this semiconductor system is not suited for higher breakdown voltages, as required, for example, for use in a 42 volt vehicle electrical system.